Telegraph signal enciphering mechanism



0, 1946. R. D. PARKER TELEGRAPH S IGNAL ENCIPHBRING MECHANISM Filed NOV. 23. 1942 FIG! BIAS IN RELAY IN VE N TOR R.D.PARKER 81 ,4, 5

Patented Aug. 20, 1946 UNITED STATES PATENT OFFICE TELEGRAPH SIGNAL ENCIPHERING MECHANISM Ralzemond D. Parker, Brooklyn. Y., assignor to Bell Telephone Laboratories,

Incorporated,

9 Claims. 1

This invention relates to secret telegraph systems and particularly to the full automatic production of a purely random key tape for use in encipherlng and deciphering permutation code teletypewriter signals.

In a system of secret telegraphy presently known in the art, in connection with which this invention may be used, the enciphered code elements as transmitted are the resultants of the elements of the regular permutation code signals modified by the elements of what is known in the art as a key tape. The key tapes are prepared and supplied to each terminal in advance. The key tapes at each terminal are identical and are operated in synchronism. Each character element of the enciphered code may be made marking or spacing by suitable mechanism, depending upon whether each element of the regular permutation code representing the character and the corresponding element as randomly punched in the key tape are alike or unlike.

Previous proposals for making random ciphering or key tapes or equivalent devices have followed two general procedures.

In accordance with one procedure, tapes have been prepared at random manually by operators. This method has two undesirable features. First, it is laborious and time consuming. Second, it seems doubtful whether a human operator can actually prepare a mathematically random tape and the deviation from randomness may b such as to aid unauthorized parties in deciphering messages. In any case, the effort to make the tape random increases the arduousness of the task and adds a mental strain to the work.

In accordance with the second procedure, key tapes have been prepared mechanically. Mechanical devices for producing random key tape, however, are complex and expensive. As a result, few, if any, such devices have been suitable for or applied to the making of key tape. The invention herein represents an improvement over presently known mechanical devices for the preparation of key tapes. The mechanism of this invention is relatively simple and inexpensive to produce and to operate. With properly chosen noise sources the resultant key tape produced by the invention herein should be perfectly random. By this is meant that when a sufficient number, say one thousand characters, are punched in a tape by means of the mechanism described herein it should be found by actual count to contain substantially equal numbers of all of the thirty-two possible characters provided in a five-element permutation code.

An object of the invention herein is the provision of improved means for and methods of producing random key tape for use in enciphering and deciphering permutation code telegraph sig- 5 nals. Another object of the invention herein is to simplify and cheapen the mechanism required to produce purely random key tape.

A feature of the invention herein is th control of each of the punch selecting magnets of l a permutation code tape perforator by the randomly occurring noise in a separate source of noise for each punch selecting magnet. A further feature of the invention herein is the controlling of the operation of each of the punch selecting magnets 01 a multielement permutation code tape perforator by means of a separate polar relay controlled by a separate amplifier-rectifier connected to a separate source of randomly occurring noise.

These and other features of the invention will become apparent from the following description when read with reference to the associated drawing in which:

Fig. 1 shows the mechanism of this invention; 2' and Fig. 2 shows a diagram used in explaining the invention.

General description 3'0: Fig. 1 shows five amplifier-reotifiers indicated by rectangles at the left of the drawing. The input of each amplifier-rectifier is coupled to a different source of random noise by means of an independent receiver. The irregular outputs of 35. amplifiers arranged so that the gain is so high that tube and resistance noise is great may be coupled to a rectifier without employing a receiver if desired. The rectified noise currents from each of the five noise sources control the 4-0 operation of an individual polar relay. The armature of each of the polar relays assumes one or another of its two positions depending upon the intensity of the noise. It is locked in engagement with one or the other of its two contacts depending upon the position it has assumed, under the control of battery supplied once per punching cycle to either of two locking windings on the polar relay through the segments of a rotary distributor. Each of the five polar relays controls the operation of a second polar relay which, in turn, controls the energization of an individual punch selecting magnet in the tape perforator. The selecting magnets of the perforator will control their respective punches so that 55.corresponding positlons in a key tape will be punched or remain unpunched, depending upon th position assumed by the armature of each of the corresponding relays. The punch perforating magnet associated with the five selecting magnets will be energized once for each rotation of the distributor arm after the punches have been set in position to operate. those of theme punches which have been set"in= the punching position'by" the selecting magnet.

Detailed description At the left of the drawing each receiver, such as I, is coupled in any convenient manner to a separate source of random noise; The source or noise may be any convenient source; the noise produced by static in a' -radio receiver, subject, however, to requirement texplalnednheree inafter. The receiver l is coupled to an amplifier-rectifler 2. The rectified output of plifier is supplied to winding Ill of relay 3 to control the operation? or its=arnmture 4 between its'opposed ccntaets 5 and 6:, A biasing: current issupplied over: a circuitentending from ground; through battery 8;. variable resistance 9 and the winding I of relay: 3 to ground: The-magnitude of the current is adjusted'by' means-of variable resistance 9 soas to maintain the armature A of relay 3 in engagementwith each or its" two contacts 5 and.- 6 approximately one-half of the time.

Fig. 2 is a current versus time graph. The irregular line therein simulates the output current of a noise amplifier-rectifier, such as ampliher-rectifier 2when connected toa source of noise suitable for use with this invention. This source of noise' might be amplifier adjusted tohave such a high gain that tube and resistance noise is very noticeable in its: output. The horizontal line in Fig. 2 indicates the magnitude of the biasing current in" winding 1' of relay 3 relative to the rectified noise current in winding I0. A suitable source of noise for the purpose of this invention is one in which the variations above and below a fixedlevel'fiuctuate rapidly andare approximately equal in duration. Each source I- may be selected to beof a different type of noise, for example, one source may be a rapidly operated typewriter... another static from a receiver, another a musical instrument, etc. In everycase best results wilt beobtained by adjustlng the amplification until the noise from thesource results in approximatelyequal numbers of marking" and spacing: conditiom. Referencetc Fig. 2 indicates that the magnitude of the ourrent output of a: amplifier exceeds thermagw nitride or the biasingcurrentabout one-halt the time. Figi 2 is" intended toexemplify a suitable rectified noise currentpattem and a biasing cur-- rent of proper magnitude with relation to the pattern of the noise current.

The efiects of the biasing current and oi the noise amplifier output current iii-windingsland III of relay 3 arearranged try oppose each other sea-that each efieet' tends to actuate-the armature 4 of relay 3' in the opposite direction. If it is assumed; th'art t'he effect of: the biasing current in winding I tends to: actuate the I of relay 3 to engage withcontact 5- and that the effect: of theoutputcurrent of the noise amplifier inwinding ll of relay 3 tends to actuate the armaturet or relay 3 to! engage with contact 6 it is apparent that the armature willengage each! contactapproximately one-half the time.

When switckr 234:; closed power is suppliettfrompower source 29te'motcr 30. Motor decoupled 4 to drive shaft 3| through gear box 32. When motor 30 rotates the arm 26 of rotary distributor 21 is rotated. On the face of the distributor 2'! there is a continuous conducting ring 33 to which is connected at ground source of battery 41. On the face of the distributor there are also five segmented rings comprising conducting: segments 3I'to 39, inclusive, and nen=conduactinge segments 40 to 45, inclusive. As the brush arm 26 rotates current is supplied during a portion of its rotation by means of interconnected conducting brushes #8 from ring 33 to segments 34 to 39, inelusive, simultaneously. When the brushes 4B are: position. tel-bridge the gap between ring it 33' andsegment 38; a circuit may be traced from ground; tnroughbattery 41, ring 33, brushe 46, segment 38 and conductor 48 to armature 4 of relay 31 Depending upon whether or not the eftecfi in winding ill of relay 3 of the output current of the noise amplifier 2 is at the moment of suflicient. magnitude toprepondenate: ever. the eilect of. the biasing current in winding. 1 of relay 3, armature-tot. relay 3 will be. in. engage.- ment with either of. its contacts 5- or 5. It the armature A is in engagementwithicontaot B the circuit. extends through winding laof relay 3 and winding t9- of relay. IJ to ground, operating the armature H of relay 1 7+ to engage contact 16. If the annatureA-isin engagement with contact 6 the. circuit extendsthrough. contact 6, winding 50 of. relay 3 and winding. Illr of. relay H to ground, operating the armature I5 of relay l-1 toward the lett to: disengage from contact Hi. When current flows-through winding 43-01 relay 3 armature 4 is locked in engagement with contact 5. When current flowsv through winding: 50 of relay 3 armature l isr locked in engagement with contact 6 The. armature A: of relay 3 remains-locked to eithercontact 501" 5 while brush 46 traverses segment 38; As a. result of this, armature I 5 of relayr ll will: be maintained in one or the other of its two positions while brush 46 traverses segment ilflr It the armature t5 of relay I1 is in engagement with contact 16 a circult may be traced from ground.. through. battery I4T armature l5 and. contact IS-oi relay H and. through thewinding. of. selector magnetiflta ground, energizing. the selector magnet. When the winding. of the selector. magnet 23 is energized.- its associated punch. is setin. the perforating. position. The selector magnet could: of course. control; the operating. elementof someother form orrecording; device as well as punched tape such. as amagnetizedtapeor disc.

Each of punch selecting. magnets 21 to will be controlledsinmltaneously in the same manner as described. for punch. selecting magnet 20 by means of corresponding independent noise sources, amplifier-recliners, rotary distributor segments and relays as shown. on th drawing.

As brush 4&- sweeps over. segment 39- a circuit is established from ground, tlsirough battery 4:1, ring 33, brushx 45; segment 38, conductor it and the winding. at punch perforating magnet 2.5- to ground, operating the perforating mechanism. Each of the punchesthat has been set in the punching position. will perfiorate the tape in cor responding positions and th tape will be moved into the: suceeding. position; irr a well-known manner. Rotaryarm- 36 rotates clockwise-as indicated by the arrow. Segment 33: subtends a smaller arc than the other cmrdnctimgsegments 34 to 38' and brush 46 engages it later'than it engages segments 34- to 38 to prostate time for the'settmg oi" the punches before magnet 25 is energized.

The armature A of relay 3 will remain locked in position in engagement with either contact 5 or contact 6 until the rotary arm 25 has swept brush 46 onto the non-conducting segments 44. If magnet 20 is energized it will remain energized for substantially the same interval. When brush 46 sweeps onto the non-conducting segments, relay 4 will be unlocked. The armature 4 of relay 3 will then be free to assume position for the next character.

Each of the other circuits controlling selectin magnets 21 to 25 will be released simultaneously in a corresponding manner.

What is claimed is:

i. In a mechanism for producing key tape for enciphering permutation code telegraph signals a plurality of means for punching a tape in a plu rality of positions, a plurality of sources of noise and a plurality of means individually responsive to variations in the intensity of noise in said plurality of sources for controlling said punching means individually.

2. In an enciphering mechanism for controlling the enciphering of a plurality of elements of a multielement permutation telegraph code combination a plurality of separate independent sources of noise, a plurality of noise receiving means connected individually to said sources and means responsive to the variation in the noise in said sources for controlling variations in the individual elements of said permutation code combination.

3. In a mechanism for producing key tape for enciphering permutation code telegraph signals a plurality of separate independent sources of noise. a plurality of noise receivers connected individually to said sources, a plurality of amplifierrectiflers responsiv individually to said receivers and a plurality of means responsive to said amplifier-rectifiers for determining the character of individual elements in a particular code combination recorded in said key tape.

4. In an enciphering mechanism for preparing key tape for enciphering permutation code telegraph signals a number of selecting mechanisms corresponding to the number of elements in a particular permutation code, means for controlling said elements comprising an amplifierrectifler individual to each or said elements and means for controlling said rectiflers individually in response to variations in noise in individual noise sources.

5. In a mechanism for manufacturing key tape for enciphering permutation code telegraph signals a polar relay, means responsive to variations in noise for controlling the operation of said relay, a pair of opposed contacts on said relay and a second control means comprising a biasing winding on said relay for maintaining the armature of said relay in engagement with a particular one of said contacts approximately one-half of the time.

6. In a mechanism for manufacturing key tape for enciphering permutation code telegraph signals a polar relay, a first control on said relay responsive to variations in noise, a second control on said relay comprising a biasing winding, a third control on said relay comprising a locking path connected to a first contact on said relay and a fourth control on said relay comprising a second locking path connected to a second contact on said relay.

7. In a mechanism for manufacturing key tape for use in enciphering permutation code telegraph signals, a plurality of amplifiers connected to a plurality of noise sources, a plurality of polar relays individually responsive to variations in the noise in said sources, a transmitting distributor, means comprising said distributor and a plurality of locking windings on each of said relays for locking the armatures of said relays in either of their alternate positions and means for energizing a plurality of selecting magnets in response to the operation of said relays.

8. In a mechanism for producing key tape for enciphering permutation code telegraph signals, a plurality of amplifiers set at inordinate gain to produce noise, a tape producing recording means and means interconnecting said amplifiers and said recording means for controlling said recordin means in response to noise variations in said amplifiers.

9. The method of producing permutated sets of two conditions which comprises selectively determining each condition of the set as a function of a characteristic at a given instant of a given source of noise and combining the two conditions thus determined in permutations.

RALZEMOND D. PARKER. 

